Copying Multi Field Tag to Comments Field

I am trying to setup my music library so that it displays properly on all devices. I have setup a custom tag, %VOCALS%, to displaying the singer and sometimes there are multiple singers. If I have one field tagged under vocals it works fine but if I have two or more it only copies over the first tag but not the second tag. What I want to do is have it so that it would move the multiple fields to the comments field and display looking like this for example: "Vocals: Mei Ayakura; Tsubaki Ichimatsu" with ; being the separator of the two fields.

If anyone can help me out that would be great.

Thanks.

You should define an action group with 2 actions.
First merge the duplicate fields:

Action Type: Merge duplicate fields
Field: VOCALS
Separator: ;

After that you move the content to any other field you want using an action of the type "Format Value".

Action Type: Format Value
Field: COMMENT
Format String: Vocals;
(Remark: There is a space after the ; )

But you should have a look at the tag-fiels INVOLVEDPEOPLE.
Maybe this suits for your needs and it is an official ID3V2.3 tag.
http://help.mp3tag.de/main_tags.html#IPLS
http://id3.org/id3v2.3.0#Involved_people_list

I was able to get it to work properly by copying what I had to do to get it to display properly under the Vocals column.

Field: COMMENT
Format String: Vocals: $meta_sep(vocals,; )